The water in Weeki Wachee Spring (which fuels the park) is a constant 76 degrees year-round. That makes it exceptionally cool in the summer. When swimming out to the dock, it's generally a good idea to sit and talk for a bit to let the cool water dry from your skin. That way, when you jump back in the water, it's cold again.

Anyway, a few friends and I were sitting on the dock, just talking about stuff. General bullshitting. I notice a fairly attractive girl to my left, sitting alone. I turn to her, smile, and say "Hi!"

Not being quite the response I expected, I managed to utter an "Um, okay then. I was just saying Hello. A return greeting would have sufficed.", and turn the conversation back to my also-shocked friends.

Generally speaking, men are stronger and more aggressive than women.
As a consequence, women depend more on their social lives, on relationships, for their own well-being.

This has implications at the social level.
In many social groups, communities, cultures, this fact of life is codified into social values, and women are expected to be married or have boyfriends, they are expected not to be alone; their respectability depends on it.

It also has implications at the personal level. I know women who - quite apart from what anyone else thinks - personally find the idea of being without a boyfriend unacceptable. Their self-esteem depends on the idea of having a boyfriend.

Now consider yourself in the situation described above: an attractive woman, alone, approached on the beach by someone who carries the nickname of Accipiter, his friends lur(k?)ing in the background. Yes, she's interested in having a good time. But she's not interested in playing the role of fair game, she wants to maintain some control over the situation. Under these circumstances, saying she has a boyfriend is a sensible thing to do, the next best thing to actually having one.

PS to Accipiter: 1) yes, I agree it's rude 2) accipiter is a bird of prey